Outline

Objective: The natural history of infratentorial arteriovenous malformations (AVMs) is linked with a worse prognosis than supratentorial AVMs. The aim of this study is to review our experience with the microsurgical treatment of these lesions.

Methods: From 1990 to 2007, 237 patients with cerebral AVMs were treated surgically in Verona. 19 of these had cerebellar AVMs. Seventeen patients presented with intracerebral hemorrhage, two patients with vertigo. According to pre-operative angiography and MRI, cerebellar AVMs were classified into 4 groups: 1) superior (10 cases), 2) inferior (6 cases), 3) lateral or cerebello-pontine angle (2 cases), holohemispheric (1 case). The AVM volume was within 20 cm3 in 17 patients, and over 20 cm3 in 2 patients. Eight patients were submitted to one or more preoperative embolization procedures. Preoperative neurological examination was negative in 6 patients; 8 patients presented neurological impairment (mainly cerebellar deficits) and 5 patients were admitted in coma, with large hematomas. A midline suboccipital approach was done in 17 cases, reserving a retrosigmoid approach for 2 patients with laterally located AVMs.

Results: The AVM was totally resected in 17 patients, as shown by postoperative angiography (in one patient the AVM was resected after embolization and radiosurgery). In 2 patients with a small residual AVM after microsurgery, subsequent radiosurgery led to complete disappearance of the AVM. At follow-up, 15 patients had a favourable outcome (13 Rankin 1 and 2 Rankin 2), 2 patients had a moderate disability (Rankin 3 and 4 respectively) and one patient a severe disability. One patient – operated in coma – died of ventriculitis a few months later.

Conclusions: Direct microsurgical excision is advised for all cerebellar AVMs, especially considering the high risk of hemorrhage for untreated patients and the low surgical morbidity. The association radiosurgery + surgery should be considered in selected cases with very large AVMs.